Just a note to add
If you find that you do get it up and running on the 450w psu you can use afterburner to drop the voltage down to 1v (from 1.178) on most of the 280's to run @ stock speeds
It reduces power draw and heat significantly, mine has been running like this for years now >.> I really must grab a new card one day.

I got it on my 450 watt. How do I go about unlocking the voltage slider in MSI Afterburner?

EDIT: Got it, mine was at 1.187 volts Set it to 1 volt, but I have to go to bed. I will do more stability testing tomorrow.Edited by TB13 - 11/14/11 at 9:51pm

Alright, so I got home from school today and decoded to do some testing. I fired up BF3 and it ran perfectly until a giant explosion went off in front of me, which crashed my system. So I decided to try and hook up the other PSU, but when I did I got a bunch of lines down my monitor. Now to my question. I guess I need to get a new PSU

Alright, so I got home from school today and decoded to do some testing. I fired up BF3 and it ran perfectly until a giant explosion went off in front of me, which crashed my system. So I decided to try and hook up the other PSU, but when I did I got a bunch of lines down my monitor. Now to my question. I guess I need to get a new PSU

that does not look good. lines with the monitor means you could've damaged the graphics card.